JP2003042159A - Dynamic pressure bearing device provided with purifying function for lubricant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device capable of removing foreign materials from a lubricating liquid without use of a filter and continuously supplying the clean lubricating liquid having no foreign materials into the clearance of the bearing. SOLUTION: A fixing member, a rotary member, and a bearing clearance in which a lubricant is introduced in between the fixing member and the rotary member, are formed. A high pressure fluid lubricating film is formed in the bearing clearance in correspondence with the rotation of the rotary member. The bearing device is constituted of the dynamic pressure bearing rotatably supporting the rotary member on the fixing member, a centrifugal separation chamber installed in the rotary member at a displaced position from the rotary center of the rotary member, an introduction flowing path introducing the lubricant with respect to the centrifugal separation chamber, a discharge passage extending from the centrifugal separation chamber to the radial outside of the rotary member, and the supplying passage supplying the lubricant from the centrifugal separation chamber to the bearing clearance of the dynamic pressure bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a high-pressure fluid lubrication film in a bearing gap between a fixed member and a rotary member by relative rotation of the fixed member and the rotary member, and holds both members in a non-contact manner. The present invention relates to a dynamic pressure bearing device that supports the rotation of the rotating member.

[0002]

2. Description of the Related Art Conventionally, as a dynamic pressure bearing device of this type,
JP-A-6-241222 and JP-A-6-24923.
The ones disclosed in Japanese Patent Laid-Open No. 6 and Japanese Patent Laid-Open No. 7-19236 are known. Such a dynamic pressure bearing device is composed of a housing fixed to a spindle head of a machine tool, a spindle connected to a drive means and rotating, and a rotary side member and a fixed side member facing each other with a predetermined bearing gap. In addition, a radial dynamic pressure bearing and a thrust dynamic pressure bearing that rotatably support the main shaft with respect to the housing are provided, and a rotary side member of each dynamic pressure bearing has a depth of approximately 10 to 15 μm for generating dynamic pressure. The grooves are formed in a predetermined pattern.

In the hydrodynamic bearing device thus constructed, the lubricating liquid present in the bearing gap of the hydrodynamic bearing is pressurized as the main shaft rotates, and the main shaft is floated by the high-pressure fluid lubrication film. , The rotation is supported in that state. For this reason, only a very slight rotational resistance acts on the rotation of the main shaft, and vibration during rotation hardly occurs. Therefore, the main shaft is used by applying a high-speed rotation of 10,000 rpm or more per minute. It has the excellent characteristics that it can also be used.

On the other hand, in such a dynamic pressure bearing device, since the lubricating liquid is pressurized as the main shaft rotates, if the bearing gap between the rotary side member and the fixed side member of each dynamic pressure bearing is too large, The pressure of the lubricating liquid cannot be sufficiently increased in the bearing gap, and the load capacity and rigidity of the main shaft against an external load will be reduced. Therefore, in the above-described conventional bearing device, the bearing gap is set to about several μm so that the lubricating liquid can be sufficiently pressurized even when the main shaft rotates at a low speed.

[0005]

By the way, in such a dynamic pressure bearing device, since the bearing gap between the rotating side member and the fixed side member of each dynamic pressure bearing is extremely small, dust or the like is added to the lubricating liquid supplied to this bearing gap. When the foreign matter is mixed in, the foreign matter is caught in the bearing gap, and the main shaft fixed to the rotating side member cannot rotate, or the dynamic pressure formed on the rotating side member or the fixed side member. There was a problem that the generation groove was damaged. For this reason, in the conventional dynamic pressure bearing device, the foreign matter mixed in the lubricating liquid is filtered off by the filter, and after that, the lubricating liquid is supplied to the bearing gap (JP-A-11-101226).

However, since the filter of the filter for removing foreign matters caught in the bearing gap having a width of about 10 μm has an extremely fine mesh, clogging is likely to occur, and the filter is sufficient per unit time with respect to the bearing gap. In order to supply the quantity of lubricating liquid, it was necessary to regularly clean the clogging of the filtration filter. For this reason, when using such a hydrodynamic bearing device as the spindle of a machine tool, it is necessary to interrupt the processing of the work piece every predetermined time to clean the filtration filter. It was one of the causes of worsening efficiency.

The present invention has been made in view of the above problems, and an object of the present invention is to remove foreign matter from a lubricating liquid without using a filtration filter, and to perform clean lubrication from which the foreign matter is removed. It is an object of the present invention to provide a dynamic pressure bearing device capable of continuously supplying a liquid to a bearing gap.

[0008]

In order to achieve the above object, in a dynamic pressure bearing device of the present invention, a fixed member, a rotary member, and a lubricating liquid is introduced between the fixed member and the rotary member. A dynamic pressure bearing that forms a bearing gap, forms a high-pressure fluid lubrication film in the bearing gap as the rotary member rotates, and rotatably supports the rotary member with respect to a fixed member, and the rotary member. The centrifuge chamber provided in the rotating member at a position displaced from the center of rotation of the rotating member, an introduction flow path for guiding the lubricating liquid to the centrifuge chamber, and a radial direction outer side of the rotating member from the centrifuge chamber. And a supply passage that is connected to the centrifugal separation chamber on the inner diameter side of the discharge passage and that supplies the lubricating liquid to the bearing gap of the dynamic pressure bearing from the centrifugal separation chamber. It is characterized by that.

According to such technical means, the lubricating liquid is introduced into the centrifugal separation chamber provided in the rotating member before being supplied to the bearing gap of the dynamic pressure bearing. Since the member is provided at a position displaced from the center of rotation of the member, centrifugal force acts on the lubricating liquid in the centrifuge chamber during rotation of the rotating member. Therefore, when foreign matter is mixed in the lubricating liquid introduced into the centrifuge chamber, the foreign matter is separated from the lubricating liquid in the centrifuge chamber due to the difference in centrifugal force acting, and the foreign matter of the rotating member It is discharged to the outside through a discharge passage extending outward in the radial direction. On the other hand, the lubricating liquid from which foreign matter has been separated by the centrifugal force is supplied to the bearing gap of the dynamic pressure bearing through the supply passage connected to the centrifugal separation chamber on the inner diameter side of the discharge passage. As a result, even when foreign matter is mixed in the lubricating fluid supplied to the centrifuge chamber, it is possible to supply clean lubricating fluid from which foreign matter has been removed to the bearing gap of the dynamic pressure bearing. Therefore, it is possible to avoid the trouble that foreign matter is caught in the bearing gap. For this reason,
Even the lubricating liquid once discharged from the dynamic pressure bearing and mixed with foreign matter such as dust can be recirculated and used as the lubricating liquid.

The present invention not only removes foreign matters such as dust from the lubricating liquid, but also utilizes the difference in specific gravity of the lubricating liquid in which two insoluble liquids such as water and oil are mixed. Alternatively, only the liquid having a low specific gravity can be used as the lubricating liquid. Therefore, even if the water used as the lubricating liquid is discharged from the dynamic pressure bearing and the lubricating oil of the mechanical device mixes with it, the lubricating oil is separated in the centrifuge chamber and only water is collected. It becomes possible to supply and use the bearing gap.

In the hydrodynamic bearing device of the present invention having such a structure, the greater centrifugal force acting on the lubricating liquid in the centrifugal separation chamber effectively removes the foreign matter in the lubricating liquid. From this point of view, the centrifuge chamber is preferably provided at a position farther from the center of rotation of the rotating member. For example, when the thrust disk is fixed to the rotary shaft and the thrust dynamic pressure bearing is constituted by the thrust disk and the fixing member, it is preferable to provide a centrifugal separation chamber for the thrust disk.

Further, in order to effectively remove foreign matter from the lubricating liquid in the centrifuge chamber, it is necessary for the lubricating liquid to stay in the centrifuge chamber for a certain period of time. Of the lubricating oil is reduced, and the lubricating liquid containing foreign matter is supplied to the bearing gap of the dynamic pressure bearing. Therefore, from this point of view, a throttle portion that adjusts the flow rate of the lubricating liquid that flows into the discharge passage is provided between the centrifugal separation chamber and the discharge passage to adjust the retention time of the lubricating liquid in the centrifugal separation chamber. Preferably.

Further, according to the present invention, when the rotating member stops, the centrifugal separation action does not work on the lubricating liquid in the centrifugal separation chamber, and the lubricating liquid is sucked from the centrifugal separation chamber into the bearing gap of the dynamic pressure bearing when the rotating member is started. Then, there is a concern that foreign matter dispersed in the lubricating liquid may be sucked together. Therefore, it is preferable to provide an occlusion body that absorbs the lubricating liquid in the supply passage so that the clean lubricating liquid from which foreign matter has been removed can be retained in the supply passage even after the rotation member is stopped. According to this structure, at the time of starting the rotating member, the clean lubricating liquid held in the occlusion body is supplied to the bearing clearance until the lubricating liquid in the centrifuge chamber has a sufficient centrifugal action. Is possible.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The dynamic bearing device of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows the first of the present invention.
1 illustrates an embodiment, in which the present invention is applied to a bearing portion of a spindle device used in a machine tool or the like. In this spindle device, a spindle main shaft 2 which is rotated at a high speed by a motor 1 is supported by a housing 5 via a radial dynamic pressure bearing 3 and a thrust dynamic pressure bearing 4, and the radial dynamic pressure bearing 3 and the thrust dynamic pressure bearing 4 are supported. A liquid such as water is used as the lubricating fluid. In FIG. 1, the center of rotation of the spindle main shaft 2 is shown by a chain line, and the right half from the center of rotation is omitted.

The radial dynamic pressure bearing 3 supporting the rotation of the spindle main shaft 2 with respect to the housing 5 is a bearing sleeve 6 fixed to the outer peripheral surface of the spindle main shaft 2.
And a ring portion 7 as a fixing member protruding from the housing 5, and a predetermined bearing gap (for example, 5 to 5) is provided between the outer peripheral surface of the bearing sleeve 6 and the inner peripheral surface of the ring portion 7. 15 μm) is formed. A dynamic pressure groove 8 is formed on the outer peripheral surface of the bearing sleeve 6 facing the inner peripheral surface of the ring portion 7, and when the spindle main shaft 2 rotates, the dynamic pressure groove 8 causes the ring portion 7 and the bearing sleeve 6 to move. The lubricating liquid existing in the gap, that is, the bearing gap of the radial dynamic pressure bearing 3 is pressurized, and a high-pressure fluid lubrication film is formed in the bearing gap. As a result, the spindle main shaft 2 is supported in its rotation without contacting the ring portion 7. Here, the dynamic pressure groove 8 is formed so as to press the lubricating liquid in the bearing gap to the center of the bearing sleeve 6 in the longitudinal direction as the spindle main shaft 2 rotates.

On the other hand, a pair of thrust dynamic pressure bearings 4 are provided so as to sandwich the radial dynamic pressure bearing 3, and the axial movement of the spindle main shaft 2 is restricted by these thrust dynamic pressure bearings 4, 4. The thrust dynamic pressure shaft bearing 4 includes a pair of thrust discs 9 and 9 fixed to the spindle main shaft 2 with the bearing sleeve 6 interposed therebetween.
It is composed of the ring portion 7 on the housing 5 side, and a predetermined bearing gap that communicates with the bearing gap of the radial dynamic pressure bearing 3 is formed between these thrust disk 9 and the axial end surface of the ring portion 7. Has been done. The spiral dynamic pressure groove 1 is formed on the axial end surface of the ring portion 7 facing the thrust disk 9.
0 is formed, and when the spindle 2 rotates,
With the dynamic pressure groove 10, the ring portion 7 and the thrust disc 9 are
Is applied, that is, the lubricating liquid present in the bearing gap of the thrust dynamic pressure bearing 4 is pressurized, and a high-pressure fluid lubrication film is formed in the bearing gap. As a result, the spindle main shaft 2 is restricted from moving in the axial direction by the pair of thrust dynamic pressure bearings 4, 4 provided with the ring portion 7 interposed therebetween.

FIG. 2 shows a dynamic pressure groove formed in the ring portion 7. The dynamic pressure groove 10 includes a spiral groove 10a of a so-called pump-in pattern that pressurizes the lubricating liquid in the bearing gap inward in the radial direction as the spindle main shaft 2 rotates, and the bearing gap as the spindle main shaft 2 rotates. And a spiral groove 10b of a so-called pump-out pattern that pressurizes the lubricating liquid toward the outside in the radial direction. The lubricating liquid is supplied to the thrust disk 9 at the boundary between the spiral grooves 10 and 10b. It is supplied from the flow path 11 to the bearing gap. Therefore, a part of the lubricating liquid guided from the supply passage 11 to the bearing gap of the thrust dynamic pressure bearing 4 is sent inward in the radial direction by the spiral groove 10a of the pump-in pattern and then the bearing gap of the radial dynamic pressure bearing 3. The other lubricating liquid is sent to the outside in the radial direction by the spiral groove 10b of the pump-out pattern, and is discharged from the outer peripheral edge of the thrust disk 9. Therefore, during rotation of the spindle main shaft 2, there is no concern that dust or the like will enter the bearing gap of the thrust dynamic pressure bearing 4 from the outside, and the radial dynamics in which both shaft ends are blocked by the thrust dynamic pressure bearing 4 There is no concern that dust will enter the bearing gap of the pressure bearing 3. The white arrows in FIG. 1 indicate the flow direction of the lubricating liquid in the bearing gap between the thrust dynamic pressure bearing 4 and the radial dynamic pressure bearing 3, and the arrow in FIG. The rotation direction of the thrust disk 9 is shown.

In the spindle device of this embodiment, the supply of the lubricating liquid to the bearing gap between the radial dynamic pressure bearing 3 and the thrust dynamic pressure bearing 4 is carried out via the centrifugal separation chamber 12 provided in each thrust disk 9. That is, the lubricating liquid is introduced into the centrifugal separation chamber 12 of the thrust disk 9 from the introduction flow passage 13 provided in the spindle main shaft 2 and then into the bearing gap of the thrust dynamic pressure bearing 4 via the above-mentioned supply flow passage 11. Supplied. A fixed side supply passage 14 is provided in the housing 5 so as to penetrate the ring portion 7 in the radial direction, and the lubricating liquid is supplied from the fixed side supply passage 14 to the spindle device. The fixed-side supply passage 14 communicates with the bearing gap of the radial dynamic pressure bearing 3. Further, the bearing sleeve 6 fixed to the spindle main shaft 2 is provided with a receiving port 15 opposed to the fixed side supply passage 14, and the receiving port 15 is provided in the spindle main shaft 2 and the introducing passage 13 is provided.
Is in communication with. The fixed side supply passage 14 is the housing 5
Although only one opening is provided for the ring portion 7 of the above, the plurality of receiving ports 15 are provided at positions that divide the bearing sleeve 6 into several equal parts in the circumferential direction, and the spindle main shaft 2 is rotating. Also, the lubricating liquid can be sent to the introduction passage 13 from any of the receiving ports 15. The lubricating fluid sent from the fixed side supply passage 14 is the radial dynamic pressure bearing 3
Flowing into the receiving port 15 through the bearing gap of the radial dynamic pressure bearing 3 as described above, the lubricating liquid in the bearing gap of the radial dynamic pressure bearing 3 is the center of the bearing sleeve 6 in the longitudinal direction, that is, the receiving port 1.
Since it is pressurized toward the opened position of 5, the lubricating liquid jetted from the fixed-side supply passage 14 into the bearing gap of the radial dynamic pressure bearing 3 cannot diffuse in the bearing gap, and most of it cannot be diffused. Will enter the receiving port 15. Also,
From the bearing clearance of the thrust dynamic pressure bearing 4 to the radial dynamic pressure bearing 3
The lubricating liquid that has flowed into the bearing gap also flows into the receiving port 15 of the bearing sleeve 6 for the same reason.

FIG. 3 shows the pressure gradient in the bearing gap between the radial dynamic pressure bearing 3 and the thrust dynamic pressure bearing 4. In the bearing gap of the radial dynamic pressure bearing 3, the pressure is highest at the center of the bearing sleeve 6 in the longitudinal direction (ΔP ₂ ), and in the bearing gap of the thrust dynamic pressure bearing 4 at the outer peripheral edge of the thrust disc 9. High pressure (ΔP ₁ ). Therefore, in order for the lubricating liquid supplied from the fixed side supply passage 14 to pass through the bearing gap of the radial dynamic pressure bearing 3 and flow into the receiving port 15, the supply pressure P ₁ of the lubricating liquid in the fixed side supply passage 14 is changed to the radial movement. It must be smaller than the maximum pressure ΔP ₂ in the pressure bearing 3. As a result, the above-described flow of the lubricating liquid is generated in the bearing gap between the radial dynamic pressure bearing 3 and the thrust dynamic pressure bearing 4, and all the lubricating liquid can be supplied to the bearing gap via the centrifugal separation chamber 12. Becomes

The lubricating liquid thus fed into the introduction passage 13 of the spindle main shaft 2 is supplied to the centrifugal separation chamber 12 provided in the thrust disc 9. FIG. 4 shows the details of the centrifuge chamber 12. The centrifuge chambers 12 are provided at several positions in the circumferential direction of the thrust disk 9, and the lubricating liquid guided from the introduction flow path 13 is temporarily stored therein.
A discharge flow path 16 is provided from the centrifugal separation chamber 12 toward the outer side in the radial direction of the thrust disk 9, and the discharge flow path 16 is provided.
Are open on the outer peripheral surface of the thrust disk 9. The centrifuge chamber 12 has a tapered throttle portion 1 facing the discharge channel 16.
7 is formed, and the presence of the throttle portion 17 allows the lubricating liquid introduced from the introduction flow path 13 to the centrifugal separation chamber 12 to temporarily stay in the centrifugal separation chamber 12.
Further, the supply flow passage 11 for supplying the lubricating liquid to the bearing gap of the thrust dynamic pressure bearing 4 is located at a position opposite to the discharge flow passage 16 with the introduction flow passage 13 sandwiched therebetween, that is, at the radially inner side of the thrust disc 9. It communicates with the centrifuge chamber 12.

When the spindle 1 is rotated by the motor 1, centrifugal force acts on the lubricating liquid in the centrifuge chamber 12, and the lubricating liquid is discharged from the discharge passage 16. During the rotation of 2, the lubricating liquid is sucked into the centrifuge chamber 12 from the introduction channel 13 as indicated by the arrow A in FIG. At this time, if there is no flow path resistance in the flow path from the introduction flow path 13 to the discharge flow path 16,
The lubricating liquid immediately passes through the centrifuge chamber 12 and the discharge flow path 16
Will flow into. However, as described above, the centrifuge chamber 12
When the throttle portion 17 is provided in the centrifuge chamber 12, the flow velocity of the lubricating liquid flowing into the centrifuge chamber 12 becomes slow in the centrifuge chamber 12 and the lubricant passes through the centrifuge chamber 12 at a slow speed. Therefore, the lubricating liquid is subjected to sufficient centrifugal force in the centrifugal separation chamber 12. If foreign matter such as metal powder is mixed in the lubricating fluid, the centrifugal force acting on the foreign matter is larger than the centrifugal force acting on the lubricating fluid because the specific gravity of the foreign matter is larger than the specific gravity of the lubricating fluid. The foreign matter moves in the lubricating liquid at a speed higher than the flow velocity of the lubricating liquid. Therefore, in the centrifuge chamber 12 during rotation, foreign matter gathers radially outside the thrust disc 9, that is, at a position close to the discharge passage 16, and inside the thrust disc 9 radially, that is, in the supply passage 11. At a close position, there is a clean lubricating liquid from which foreign matter has been removed. In other words, the centrifugal action acts on the foreign matter in the lubricating liquid, and the introduction flow path 13
The lubricating liquid supplied to the centrifugal separation chamber 12 from is separated into a lubricating liquid in which foreign matter is mixed and a clean lubricating liquid in which foreign matter is not mixed. The lubricating liquid containing a large amount of foreign matter is shown in FIG.
As indicated by the arrow B in the drawing, the lubricating liquid discharged from the centrifugal separation chamber 12 through the discharge flow passage 16 is combined with the lubricating liquid discharged from the bearing clearance of the thrust dynamic pressure bearing 4, and 5 is sent out of the apparatus through the fixed discharge path 18. On the other hand, the clean lubricating liquid from which the foreign matter has been removed is sucked into the supply passage 11 as indicated by the arrow C and supplied to the bearing gap of the thrust dynamic pressure bearing 4.

Whether or not the amount of the clean lubricating liquid from which foreign substances have been removed can be supplied depends on the total flow rate of the lubricating liquid, the cross-sectional area of the throttle portion, the capacity of the centrifuge chamber, and the centrifuge chamber. Connection position of supply channel, rotation speed of spindle spindle,
It is determined by the radial position of the centrifugation chamber. Since the flow rate of the lubricating liquid used in the dynamic pressure bearing is much smaller than the total flow rate of the lubricating liquid, various parameters should be determined so as to satisfy this flow rate.

As a result, in the spindle device according to the present embodiment, even if the lubricating liquid mixed with foreign matter such as dust is supplied from the fixed side supply passage 14 of the housing 5, the clean lubricating liquid is obtained by removing the foreign matter by the centrifugal action. Only thrust dynamic bearing 4
And since it can be supplied to the bearing clearance of the radial dynamic pressure bearing 3, it is possible to avoid the trouble that the foreign matter is caught in the bearing clearance without providing a filter for filtering the foreign matter. Becomes

When the spindle main shaft of the spindle device of the machine tool is supported by the dynamic pressure bearing, there is a possibility that foreign matter such as cutting powder of the work is mixed in the lubricating liquid discharged from the dynamic pressure bearing. In the spindle device of the present embodiment described above, this lubricating liquid is collected and re-supplied as the lubricating liquid as it is without passing through any filtration filter, and the operation of such a machine tool can be continued. It is possible to reduce the operating cost by significantly reducing Further, since the lubricating liquid can be reused without using the filtration filter, it is not necessary to suspend the operation for cleaning the filtration filter, and the operation efficiency of the spindle device can be improved.

On the other hand, since the centrifugal separation action does not work on the lubricating liquid in the centrifugal separation chamber 12 while the spindle main shaft 2 is stopped, the lubricating liquid containing foreign matter may flow into the supply passage 11. However, in order to eliminate this possibility in the present embodiment, an occlusion body 19 that absorbs and retains the lubricating liquid is provided at the inlet of the supply channel 11 in the centrifuge chamber 12 to prevent the spindle main shaft 2 from rotating during rotation. The occluded body 19 was constituted so that the cleaned lubricating liquid was contained therein. As the occlusion body 19, a cloth made of highly water-absorbent fibers, a porous resin, ceramics, a metal, or the like can be used.

According to the construction in which such an occlusion body 19 is provided in the centrifuge chamber 12, the lubricating liquid cleaned during the rotation of the spindle 2 is absorbed and retained in the occlusion body 19. Even when the spindle main shaft 2 is started after the rotation thereof is once stopped, the spindle main shaft 2 is started while supplying the clean lubricating liquid contained in the occlusion body 19 to the bearing gap of the thrust dynamic pressure bearing 4. It can be performed.

In the spindle device of the first embodiment, not only when solid foreign matter such as dust is mixed in the lubricating liquid, but also water such as the lubricating liquid of the machine tool is absorbed by the water as the lubricating liquid. It is also effective when mixed.

Next, FIG. 5 shows a second embodiment of the present invention, in which the present invention is applied to a bearing portion of an impeller of a cascade pump. This cascade pump is configured to rotate an impeller 31 housed in a housing 30 and to pump a liquid in a working passage 32 formed in the housing 30. A motor 33 that drives the wheel 31 is provided integrally with the housing 30 and the impeller 31. That is, the motor rotor 33 a is directly fixed to the impeller 31, while the housing 30 that accommodates the impeller 31.
A motor stator 33b is fixed to the motor rotor 33b, and the impeller 31 is directly driven to rotate by a drive motor 33 composed of the motor rotor 33a and the motor stator 33b. In FIG. 5, the center of rotation of the impeller 31 is shown by a chain line, and the lower side of the center of rotation is omitted.

A plurality of action grooves 34 are arranged on the outer circumference of the impeller 31 along the circumferential direction. This working groove 34
Is formed on one corner where the side surface and the outer peripheral surface of the impeller 31 intersect, and is formed by cutting out the corner of the impeller 31 in a fan shape. On the other hand, the working passage 32
Is formed so as to accommodate the formation region of the action groove 34 of the impeller 31, and the cross section of the action passage 32 widely surrounds the outside of the action groove 34 of the impeller 31.

FIG. 6 is a sectional view showing the relationship between the working passage 32 formed in the housing 1 and the impeller 31. The working passage 32 is provided so as to surround about 80% of the outer circumference of the impeller 31, and a suction passage 35 for guiding the liquid to the working passage 32 is provided at one end thereof, and a pumped liquid is provided at the other end thereof. The discharge passage 36 for discharging is connected. In addition, the suction passage 35 and the discharge passage 36
A partition wall 37 is formed between the partition wall 37 and the outer wall surface of the impeller 31 (for example, 20 μm).
(To the extent) opposite. As a result, the working passage 3
The suction side and the discharge side of 2 are separated from each other to prevent the liquid in the discharge passage 36 side from returning to the suction passage 35 side.

In order to prevent the liquid in the working passage 32 from leaking from the side surface of the impeller 31 toward the center of rotation, on the inner diameter side of the working passage 32, the impeller 31 and the housing 30 have a very small gap. Are facing through. In this embodiment, the thrust dynamic pressure bearing 38 is formed between the side surface of the impeller 31 and the housing 30 by using this gap as a bearing gap. Further, the back surface of the impeller 31 provided with the motor rotor 33a also faces the housing 30 with a slight gap, and constitutes a thrust dynamic pressure bearing 39 having the gap as a bearing gap. As a result, the impeller 31 is restricted from moving in the axial direction by the pair of thrust dynamic pressure bearings 38 and 39.

Similar to the first embodiment, the dynamic pressure grooves formed on both side surfaces of the impeller 31 press the lubricant in the bearing gap radially inward as the impeller 31 rotates. The spiral groove of the pump-in pattern and the so-called pump-out pattern spiral groove that pressurizes the lubricant in the bearing gap outward in the radial direction as the impeller 31 rotates are used. It is supplied to the bearing gap from the supply flow path 40 opened in the impeller at the boundary of the groove. Therefore, a part of the lubricating liquid guided from the supply passage 40 to the bearing gaps of the thrust dynamic pressure bearings 38, 39 is sent to the inner side in the radial direction by the spiral groove of the pump-in pattern, and the bearing of the radial dynamic pressure bearing described later is obtained. It flows into the gap. Further, the other lubricating liquid is sent to the outside in the radial direction by the spiral groove of the pump-out pattern, and is discharged from the outer peripheral edge of the impeller 31 into the working passage 32. Therefore, during rotation of the impeller 31, there is no concern that dust or the like will enter from the working passage 32 into the bearing gap between the thrust dynamic pressure bearings 38, 39.

The inner peripheral surface of the impeller 31 is the housing 3
0 and a radial dynamic pressure bearing 41, which is opposed to 0 through a slight gap, and which serves as a bearing gap. A dynamic pressure groove for pressurizing the lubricating fluid in the bearing gap is formed in the housing 30, and when the impeller 31 starts rotating,
A high-pressure fluid lubrication film is formed in the bearing gap, and the rotation of the impeller 31 is supported in a non-contact state with the housing 30. Here, the dynamic pressure groove is formed so as to press the lubricating liquid in the bearing gap toward the center of the impeller 31 in the axial direction (width direction) as the impeller 31 rotates. The white arrows in FIG. 5 indicate the flowing direction of the lubricating liquid in the bearing gaps of the thrust dynamic pressure bearings 38, 39 and the radial dynamic pressure bearing 41.

In each of the thrust dynamic pressure bearings 38, 39 and the radial dynamic pressure bearing 41, the liquid that is pumped in the working passage 32 is used as the lubricating liquid. The housing 30 is formed with a fixed-side supply passage 42 for extracting the lubricating liquid from the working passage 32, and the lubricating liquid is supplied to the impeller 31 from the fixed-side supply passage 42.
The fixed side supply passage 42 communicates with the bearing gap of the radial dynamic pressure bearing 41. Further, the impeller 31 is provided with an introduction flow path 43 facing the fixed side supply path 42, and the introduction flow path 43 communicates with a centrifugal separation chamber 44 provided in the impeller 31. The lubricating liquid sent from the fixed-side supply passage 42 flows into the introduction passage 43 through the bearing gap of the radial dynamic pressure bearing 41, but as described above, the lubricating liquid is impeller in the bearing gap of the radial dynamic pressure bearing 41. Since the pressure is applied toward the center in the axial direction of 31, i.e., toward the opened position of the introduction flow passage 43, the lubricating liquid ejected from the fixed side supply passage 42 into the bearing gap of the radial dynamic pressure bearing 41 is the bearing gap. It cannot diffuse inside, and most of it will enter the introduction flow path 43. Further, the lubricating liquid flowing from the bearing gaps of the thrust dynamic pressure bearings 38 and 39 to the bearing gaps of the radial dynamic pressure bearing 41 also flows into the introduction flow passage 43 of the impeller 31 wheel for the same reason.

In this way, the introduction passage 43 of the impeller 31
The lubricating liquid sent to is supplied to the centrifugal separation chamber 44 provided in the impeller 31. FIG. 7 shows this centrifuge chamber 44.
Is shown. The centrifugal separation chambers 44 are provided at several places in the circumferential direction of the impeller 31, and the lubricating liquid introduced from the introduction flow passage 43 is temporarily stored. A discharge flow passage 45 is provided from the centrifugal separation chamber 44 toward the outer side in the radial direction of the impeller 31, and the discharge flow passage 45 is opened to the working passage 32 on the outer peripheral surface of the impeller 31. In the centrifugal separation chamber 44, a tapered throttle portion 46 is formed toward the discharge flow passage 45. Due to the presence of the throttle portion 46, the lubricating liquid introduced from the introduction flow passage 43 into the centrifugal separation chamber 44 is prevented. The centrifuge chamber 44
It is supposed to temporarily stay inside. Further, the supply passage 40 for supplying the lubricating liquid to the bearing gaps of the thrust dynamic pressure bearings 38, 39 is centrifugally arranged at a position closer to the introduction passage 43 than the discharge passage 45, that is, at the inner side in the radial direction of the impeller 31. It communicates with the separation chamber 44.

When the impeller 31 is rotated by the motor 33, the lubricating liquid in the supply passage 40 is sucked into the bearing gaps of the thrust dynamic pressure bearings 38 and 39, and the lubricating liquid in the centrifugal chamber 44 is supplied. It is sucked into the road 40. Since the centrifugal separation chamber 44 exists at a position displaced from the rotation center of the impeller 31, when the impeller 31 rotates, centrifugal force acts on the lubricating liquid in the centrifugal separation chamber 44. If this cascade pump is used to pump slurry such as grinding fluid containing abrasive grains, the specific gravity of the abrasive grains is larger than the specific gravity of the grinding fluid that becomes the lubricating fluid, so the centrifugal force that acts on the abrasive grains is The centrifugal force acting on the liquid is larger than the centrifugal force. In the rotating centrifugal separation chamber 44, the abrasive particles gather outside the impeller 31 in the radial direction, that is, at a position close to the discharge flow passage 45, and the centrifugal force in the radial direction of the impeller 31 increases. At the inner side, that is, at a position close to the supply flow path 43, there is a clean grinding liquid from which abrasive grains have been removed. That is, the centrifugal separation action acts on the abrasive particles in the grinding liquid, and the grinding liquid supplied from the introduction flow path 43 to the centrifugal separation chamber 44 is the grinding liquid mixed with the abrasive particles and the clean grinding without the mixing of the abrasive particles. It is separated into liquid. And
The grinding fluid containing a large amount of abrasive grains is discharged from the centrifugal separation chamber 44 through the discharge passage 45 and returned to the working passage 32. On the other hand, the clean grinding liquid from which the abrasive grains have been removed is sucked into the supply passage 40 and supplied to the bearing gaps of the thrust dynamic pressure bearings 38, 39.

As a result, in the cascade pump of this embodiment, even if the grinding fluid mixed with the abrasive grains is supplied from the fixed side supply passage 42 of the housing 30, only the clean grinding fluid from which the abrasive grains have been removed by the centrifugal separation action is supplied. Can be supplied to the bearing gaps of the thrust dynamic pressure bearings 38, 39 and the radial dynamic pressure bearing 41 as a lubricating liquid, so that the abrasive grains can be supplied to the bearing gaps without providing a filter for filtering the abrasive grains. It is possible to avoid troubles such as being caught.

Even in the cascade pump of the second embodiment, if it is taken into consideration when the impeller 31 is restarted after being temporarily stopped, the supply flow path in the centrifugal separation chamber 44 will be described. An occlusion body 4 which absorbs and holds a lubricating liquid at the inlet of 40
It is preferable that 7 is provided so that the occlusion body 47 contains the lubricating liquid cleaned during the rotation of the impeller 31.

[0039]

As described above, according to the dynamic pressure bearing device of the present invention, since the lubricating liquid is supplied to the bearing gap through the centrifugal separation chamber, the lubricating liquid is supplied to the centrifugal separation chamber. Even if foreign matter is mixed in the lubricating fluid to be used, it is possible to remove the foreign matter from the lubricating fluid by the centrifugal action and to supply only clean lubricating fluid to the bearing clearance. It is possible to avoid troubles such as foreign matter getting caught in the gap, removing foreign matter from the lubricating liquid without using a filtration filter, and continuously removing the foreign matter from the clean lubricating liquid to the bearing gap. Can be supplied to.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment in which the present invention is applied to a spindle device.

FIG. 2 is a diagram showing a dynamic pressure groove of the thrust dynamic pressure bearing according to the first embodiment.

FIG. 3 is a diagram showing a pressure distribution in a bearing gap of the radial dynamic pressure bearing and the thrust dynamic pressure bearing according to the first embodiment.

FIG. 4 is an enlarged sectional view showing a centrifuge chamber according to the first embodiment.

FIG. 5 is a sectional view showing a second embodiment in which the present invention is applied to a cascade pump.

FIG. 6 is a cross-sectional view showing the relationship between the impeller and the working passage of the cascade pump according to the second embodiment.

FIG. 7 is an enlarged cross-sectional view showing a centrifuge chamber according to a second embodiment.

[Explanation of symbols]

2 ... Spindle main shaft (rotating member), 3 ... Radial dynamic pressure bearing, 4 ... Thrust dynamic pressure bearing, 5 ... Housing (fixing member), 11 ... Supply channel, 12 ... Centrifuge chamber, 13 ... Introducing channel, 16 ... Discharge channel

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[Procedure amendment]

[Submission date] August 13, 2001 (2001.8.1)
3)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Detailed explanation of the invention

[Correction method] Change

[Correction content]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a high-pressure fluid lubrication film in a bearing gap between a fixed member and a rotary member by relative rotation of the fixed member and the rotary member, and holds both members in a non-contact manner. The present invention relates to a dynamic pressure bearing device that supports the rotation of the rotating member.

[0002]

2. Description of the Related Art Conventionally, as a dynamic pressure bearing device of this type,
JP-A-6-241222 and JP-A-6-24923.
The ones disclosed in Japanese Patent Laid-Open No. 6 and Japanese Patent Laid-Open No. 7-19236 are known. Such a dynamic pressure bearing device is composed of a housing fixed to a spindle head of a machine tool, a spindle connected to a drive means and rotating, and a rotary side member and a fixed side member facing each other with a predetermined bearing gap. In addition, a radial dynamic pressure bearing and a thrust dynamic pressure bearing that rotatably support the main shaft with respect to the housing are provided, and a rotary side member of each dynamic pressure bearing has a depth of approximately 10 to 15 μm for generating dynamic pressure. The grooves are formed in a predetermined pattern.

In the hydrodynamic bearing device thus constructed, the lubricating liquid present in the bearing gap of the hydrodynamic bearing is pressurized as the main shaft rotates, and the main shaft is floated by the high-pressure fluid lubrication film. , The rotation is supported in that state. For this reason, only a very slight rotational resistance acts on the rotation of the main shaft, and vibration during rotation hardly occurs. Therefore, the main shaft is used by applying a high-speed rotation of 10,000 rpm or more per minute. It has the excellent characteristics that it can also be used.

On the other hand, in such a dynamic pressure bearing device, since the lubricating liquid is pressurized as the main shaft rotates, if the bearing gap between the rotary side member and the fixed side member of each dynamic pressure bearing is too large, The pressure of the lubricating liquid cannot be sufficiently increased in the bearing gap, and the load capacity and rigidity of the main shaft against an external load will be reduced. Therefore, in the above-described conventional bearing device, the bearing gap is set to about several μm so that the lubricating liquid can be sufficiently pressurized even when the main shaft rotates at a low speed.

[0005]

By the way, in such a dynamic pressure bearing device, since the bearing gap between the rotating side member and the fixed side member of each dynamic pressure bearing is extremely small, dust or the like is added to the lubricating liquid supplied to this bearing gap. When the foreign matter is mixed in, the foreign matter is caught in the bearing gap, and the main shaft fixed to the rotating side member cannot rotate, or the dynamic pressure formed on the rotating side member or the fixed side member. There was a problem that the generation groove was damaged. For this reason, in the conventional dynamic pressure bearing device, the foreign matter mixed in the lubricating liquid is filtered off by the filter, and after that, the lubricating liquid is supplied to the bearing gap (JP-A-11-101226).

However, since the filter of the filter for removing foreign matters caught in the bearing gap having a width of about 10 μm has an extremely fine mesh, clogging is likely to occur, and the filter is sufficient per unit time with respect to the bearing gap. In order to supply the quantity of lubricating liquid, it was necessary to regularly clean the clogging of the filtration filter. For this reason, when using such a hydrodynamic bearing device as the spindle of a machine tool, it is necessary to interrupt the processing of the work piece every predetermined time to clean the filtration filter. It was one of the causes of worsening efficiency.

The present invention has been made in view of the above problems, and an object of the present invention is to remove foreign matter from a lubricating liquid without using a filtration filter, and to perform clean lubrication from which the foreign matter is removed. It is an object of the present invention to provide a dynamic pressure bearing device capable of continuously supplying a liquid to a bearing gap.

[0008]

In order to achieve the above object, in a dynamic pressure bearing device of the present invention, a fixed member, a rotary member, and a lubricating liquid is introduced between the fixed member and the rotary member. A dynamic pressure bearing that forms a bearing gap, forms a high-pressure fluid lubrication film in the bearing gap as the rotary member rotates, and rotatably supports the rotary member with respect to a fixed member, and the rotary member. The centrifuge chamber provided in the rotating member at a position displaced from the center of rotation of the rotating member, an introduction flow path for guiding the lubricating liquid to the centrifuge chamber, and a radial direction outer side of the rotating member from the centrifuge chamber. And a supply passage that is connected to the centrifugal separation chamber on the inner diameter side of the discharge passage and that supplies the lubricating liquid to the bearing gap of the dynamic pressure bearing from the centrifugal separation chamber. It is characterized by that.

According to such technical means, the lubricating liquid is introduced into the centrifugal separation chamber provided in the rotating member before being supplied to the bearing gap of the dynamic pressure bearing. Since the member is provided at a position displaced from the center of rotation of the member, centrifugal force acts on the lubricating liquid in the centrifuge chamber during rotation of the rotating member. Therefore, when foreign matter is mixed in the lubricating liquid introduced into the centrifuge chamber, the foreign matter is separated from the lubricating liquid in the centrifuge chamber due to the difference in centrifugal force acting, and the foreign matter of the rotating member is separated from the centrifugal chamber. It is discharged to the outside through a discharge passage extending outward in the radial direction. On the other hand, the lubricating liquid from which foreign matter has been separated by the centrifugal force is supplied to the bearing gap of the dynamic pressure bearing through the supply passage connected to the centrifugal separation chamber on the inner diameter side of the discharge passage. As a result, even when foreign matter is mixed in the lubricating fluid supplied to the centrifuge chamber, it is possible to supply clean lubricating fluid from which foreign matter has been removed to the bearing gap of the dynamic pressure bearing. Therefore, it is possible to avoid the trouble that foreign matter is caught in the bearing gap. For this reason,
Even the lubricating liquid once discharged from the dynamic pressure bearing and mixed with foreign matter such as dust can be recirculated and used as the lubricating liquid.

The present invention not only removes foreign matters such as dust from the lubricating liquid, but also utilizes the difference in specific gravity of the lubricating liquid in which two insoluble liquids such as water and oil are mixed. Alternatively, only the liquid having a low specific gravity can be used as the lubricating liquid.

In the hydrodynamic bearing device of the present invention having such a structure, the greater centrifugal force acting on the lubricating liquid in the centrifugal separation chamber effectively removes the foreign matter in the lubricating liquid. From this point of view, the centrifuge chamber is preferably provided at a position farther from the center of rotation of the rotating member. For example, when the thrust disk is fixed to the rotary shaft and the thrust dynamic pressure bearing is constituted by the thrust disk and the fixing member, it is preferable to provide a centrifugal separation chamber for the thrust disk.

Further, in order to effectively remove foreign matter from the lubricating liquid in the centrifuge chamber, it is necessary for the lubricating liquid to stay in the centrifuge chamber for a certain period of time. Of the lubricating oil is reduced, and the lubricating liquid containing foreign matter is supplied to the bearing gap of the dynamic pressure bearing. Therefore, from this point of view, a throttle portion that adjusts the flow rate of the lubricating liquid that flows into the discharge passage is provided between the centrifugal separation chamber and the discharge passage to adjust the retention time of the lubricating liquid in the centrifugal separation chamber. Preferably.

Further, according to the present invention, when the rotating member stops, the centrifugal separation action does not work on the lubricating liquid in the centrifugal separation chamber, and the lubricating liquid is sucked from the centrifugal separation chamber into the bearing gap of the dynamic pressure bearing when the rotating member is started. Then, there is a concern that foreign matter dispersed in the lubricating liquid may be sucked together. Therefore, it is preferable to provide an occlusion body that absorbs the lubricating liquid in the supply passage so that the clean lubricating liquid from which foreign matter has been removed can be retained in the supply passage even after the rotation member is stopped. According to this structure, at the time of starting the rotating member, the clean lubricating liquid held in the occlusion body is supplied to the bearing clearance until the lubricating liquid in the centrifuge chamber has a sufficient centrifugal action. Is possible.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The dynamic bearing device of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows the first of the present invention.
1 illustrates an embodiment, in which the present invention is applied to a bearing portion of a spindle device used in a machine tool or the like. In this spindle device, a spindle main shaft 2 which is rotated at a high speed by a motor 1 is supported by a housing 5 via a radial dynamic pressure bearing 3 and a thrust dynamic pressure bearing 4, and the radial dynamic pressure bearing 3 and the thrust dynamic pressure bearing 4 are supported. A liquid such as water is used as the lubricating fluid. In FIG. 1, the center of rotation of the spindle main shaft 2 is shown by a chain line, and the right half from the center of rotation is omitted.

The radial dynamic pressure bearing 3 supporting the rotation of the spindle main shaft 2 with respect to the housing 5 is a bearing sleeve 6 fixed to the outer peripheral surface of the spindle main shaft 2.
And a ring portion 7 as a fixing member protruding from the housing 5, and a predetermined bearing gap (for example, 5 to 5) is provided between the outer peripheral surface of the bearing sleeve 6 and the inner peripheral surface of the ring portion 7. 15 μm) is formed. A dynamic pressure groove 8 is formed on the outer peripheral surface of the bearing sleeve 6 facing the inner peripheral surface of the ring portion 7, and when the spindle main shaft 2 rotates, the dynamic pressure groove 8 causes the ring portion 7 and the bearing sleeve 6 to move. The lubricating liquid existing in the gap, that is, the bearing gap of the radial dynamic pressure bearing 3 is pressurized, and a high-pressure fluid lubrication film is formed in the bearing gap. As a result, the spindle main shaft 2 is supported in its rotation without contacting the ring portion 7. Here, the dynamic pressure groove 8 is formed so as to press the lubricating liquid in the bearing gap to the center of the bearing sleeve 6 in the longitudinal direction as the spindle main shaft 2 rotates.

On the other hand, a pair of thrust dynamic pressure bearings 4 are provided so as to sandwich the radial dynamic pressure bearing 3, and the axial movement of the spindle main shaft 2 is restricted by these thrust dynamic pressure bearings 4, 4. The thrust dynamic pressure shaft bearing 4 includes a pair of thrust discs 9 and 9 fixed to the spindle main shaft 2 with the bearing sleeve 6 interposed therebetween.
It is composed of the ring portion 7 on the housing 5 side, and a predetermined bearing gap that communicates with the bearing gap of the radial dynamic pressure bearing 3 is formed between these thrust disk 9 and the axial end surface of the ring portion 7. Has been done. The spiral dynamic pressure groove 1 is formed on the axial end surface of the ring portion 7 facing the thrust disk 9.
0 is formed, and when the spindle 2 rotates,
With the dynamic pressure groove 10, the ring portion 7 and the thrust disc 9 are
Is applied, that is, the lubricating liquid present in the bearing gap of the thrust dynamic pressure bearing 4 is pressurized, and a high-pressure fluid lubrication film is formed in the bearing gap. As a result, the spindle main shaft 2 is restricted from moving in the axial direction by the pair of thrust dynamic pressure bearings 4, 4 provided with the ring portion 7 interposed therebetween.

FIG. 2 shows a dynamic pressure groove formed in the ring portion 7. The dynamic pressure groove 10 includes a spiral groove 10a of a so-called pump-in pattern that pressurizes the lubricating liquid in the bearing gap inward in the radial direction as the spindle main shaft 2 rotates, and the bearing gap as the spindle main shaft 2 rotates. And a spiral groove 10b of a so-called pump-out pattern that pressurizes the lubricating liquid toward the outside in the radial direction. The lubricating liquid is supplied to the thrust disk 9 at the boundary between the spiral grooves 10 and 10b. It is supplied from the flow path 11 to the bearing gap. Therefore, a part of the lubricating liquid guided from the supply passage 11 to the bearing gap of the thrust dynamic pressure bearing 4 is sent inward in the radial direction by the spiral groove 10a of the pump-in pattern and then the bearing gap of the radial dynamic pressure bearing 3. The other lubricating liquid is sent to the outside in the radial direction by the spiral groove 10b of the pump-out pattern, and is discharged from the outer peripheral edge of the thrust disk 9. Therefore, during rotation of the spindle main shaft 2, there is no concern that dust or the like will enter the bearing gap of the thrust dynamic pressure bearing 4 from the outside, and the radial dynamics in which both shaft ends are blocked by the thrust dynamic pressure bearing 4 There is no concern that dust will enter the bearing gap of the pressure bearing 3. The white arrows in FIG. 1 indicate the flow direction of the lubricating liquid in the bearing gap between the thrust dynamic pressure bearing 4 and the radial dynamic pressure bearing 3, and the arrow in FIG. The rotation direction of the thrust disk 9 is shown.

In the spindle device of this embodiment, the supply of the lubricating liquid to the bearing gap between the radial dynamic pressure bearing 3 and the thrust dynamic pressure bearing 4 is carried out via the centrifugal separation chamber 12 provided in each thrust disk 9. That is, the lubricating liquid is introduced into the centrifugal separation chamber 12 of the thrust disk 9 from the introduction flow passage 13 provided in the spindle main shaft 2 and then into the bearing gap of the thrust dynamic pressure bearing 4 via the above-mentioned supply flow passage 11. Supplied. A fixed side supply passage 14 is provided in the housing 5 so as to penetrate the ring portion 7 in the radial direction, and the lubricating liquid is supplied from the fixed side supply passage 14 to the spindle device. The fixed-side supply passage 14 communicates with the bearing gap of the radial dynamic pressure bearing 3. Further, the bearing sleeve 6 fixed to the spindle main shaft 2 is provided with a receiving port 15 opposed to the fixed side supply passage 14, and the receiving port 15 is provided in the spindle main shaft 2 and the introducing passage 13 is provided.
Is in communication with. The fixed side supply passage 14 is the housing 5
Although only one opening is provided for the ring portion 7 of the above, the plurality of receiving ports 15 are provided at positions that divide the bearing sleeve 6 into several equal parts in the circumferential direction, and the spindle main shaft 2 is rotating. Also, the lubricating liquid can be sent to the introduction passage 13 from any of the receiving ports 15. The lubricating fluid sent from the fixed side supply passage 14 is the radial dynamic pressure bearing 3
Flowing into the receiving port 15 through the bearing gap of the radial dynamic pressure bearing 3 as described above, the lubricating liquid in the bearing gap of the radial dynamic pressure bearing 3 is the center of the bearing sleeve 6 in the longitudinal direction, that is, the receiving port 1.
Since it is pressurized toward the opened position of 5, the lubricating liquid jetted from the fixed-side supply passage 14 into the bearing gap of the radial dynamic pressure bearing 3 cannot diffuse in the bearing gap, and most of it cannot be diffused. Will enter the receiving port 15. Also,
From the bearing clearance of the thrust dynamic pressure bearing 4 to the radial dynamic pressure bearing 3
The lubricating liquid that has flowed into the bearing gap also flows into the receiving port 15 of the bearing sleeve 6 for the same reason.

FIG. 3 shows the pressure gradient in the bearing gap between the radial dynamic pressure bearing 3 and the thrust dynamic pressure bearing 4. In the bearing gap of the radial dynamic pressure bearing 3, the pressure is highest at the center of the bearing sleeve 6 in the longitudinal direction (ΔP ₂ ), and in the bearing gap of the thrust dynamic pressure bearing 4 at the outer peripheral edge of the thrust disc 9. High pressure (ΔP ₁ ). Therefore, in order for the lubricating liquid supplied from the fixed side supply passage 14 to pass through the bearing gap of the radial dynamic pressure bearing 3 and flow into the receiving port 15, the supply pressure P ₁ of the lubricating liquid in the fixed side supply passage 14 is changed to the radial movement. It must be smaller than the maximum pressure ΔP ₂ in the pressure bearing 3. As a result, the above-described flow of the lubricating liquid is generated in the bearing gap between the radial dynamic pressure bearing 3 and the thrust dynamic pressure bearing 4, and all the lubricating liquid can be supplied to the bearing gap via the centrifugal separation chamber 12. Becomes

The lubricating liquid thus fed into the introduction passage 13 of the spindle main shaft 2 is supplied to the centrifugal separation chamber 12 provided in the thrust disc 9. FIG. 4 shows the details of the centrifuge chamber 12. The centrifuge chambers 12 are provided at several positions in the circumferential direction of the thrust disk 9, and the lubricating liquid guided from the introduction flow path 13 is temporarily stored therein.
A discharge flow path 16 is provided from the centrifugal separation chamber 12 toward the outer side in the radial direction of the thrust disk 9, and the discharge flow path 16 is provided.
Are open on the outer peripheral surface of the thrust disk 9. The centrifuge chamber 12 has a tapered throttle portion 1 facing the discharge channel 16.
7 is formed, and the presence of the throttle portion 17 allows the lubricating liquid introduced from the introduction flow path 13 to the centrifugal separation chamber 12 to temporarily stay in the centrifugal separation chamber 12.
Further, the supply flow passage 11 for supplying the lubricating liquid to the bearing gap of the thrust dynamic pressure bearing 4 is located at a position opposite to the discharge flow passage 16 with the introduction flow passage 13 sandwiched therebetween, that is, at the radially inner side of the thrust disc 9. It communicates with the centrifuge chamber 12.

When the spindle 1 is rotated by the motor 1, centrifugal force acts on the lubricating liquid in the centrifuge chamber 12, and the lubricating liquid is discharged from the discharge passage 16. During the rotation of 2, the lubricating liquid is sucked into the centrifuge chamber 12 from the introduction channel 13 as indicated by the arrow A in FIG. At this time, if there is no flow path resistance in the flow path from the introduction flow path 13 to the discharge flow path 16,
The lubricating liquid immediately passes through the centrifuge chamber 12 and the discharge flow path 16
Will flow into. However, as described above, the centrifuge chamber 12
When the throttle portion 17 is provided in the centrifuge chamber 12, the flow velocity of the lubricating liquid flowing into the centrifuge chamber 12 becomes slow in the centrifuge chamber 12 and the lubricant passes through the centrifuge chamber 12 at a slow speed. Therefore, the lubricating liquid is subjected to sufficient centrifugal force in the centrifugal separation chamber 12. If foreign matter such as metal powder is mixed in the lubricating fluid, the centrifugal force acting on the foreign matter is larger than the centrifugal force acting on the lubricating fluid because the specific gravity of the foreign matter is larger than the specific gravity of the lubricating fluid. The foreign matter moves in the lubricating liquid at a speed higher than the flow velocity of the lubricating liquid. Therefore, in the centrifuge chamber 12 during rotation, foreign matter gathers radially outside the thrust disc 9, that is, at a position close to the discharge passage 16, and inside the thrust disc 9 radially, that is, in the supply passage 11. At a close position, there is a clean lubricating liquid from which foreign matter has been removed. In other words, the centrifugal action acts on the foreign matter in the lubricating liquid, and the introduction flow path 13
The lubricating liquid supplied to the centrifugal separation chamber 12 from is separated into a lubricating liquid in which foreign matter is mixed and a clean lubricating liquid in which foreign matter is not mixed. The lubricating liquid containing a large amount of foreign matter is shown in FIG.
As indicated by the arrow B in the drawing, the lubricating liquid discharged from the centrifugal separation chamber 12 through the discharge flow passage 16 is combined with the lubricating liquid discharged from the bearing clearance of the thrust dynamic pressure bearing 4, and 5 is sent out of the apparatus through the fixed discharge path 18. On the other hand, the clean lubricating liquid from which the foreign matter has been removed is sucked into the supply passage 11 as indicated by the arrow C and supplied to the bearing gap of the thrust dynamic pressure bearing 4.

Whether or not the amount of the clean lubricating liquid from which foreign substances have been removed can be supplied depends on the total flow rate of the lubricating liquid, the cross-sectional area of the throttle portion, the capacity of the centrifuge chamber, and the centrifuge chamber. Connection position of supply channel, rotation speed of spindle spindle,
It is determined by the radial position of the centrifugation chamber. Since the flow rate of the lubricating liquid used in the dynamic pressure bearing is much smaller than the total flow rate of the lubricating liquid, various parameters should be determined so as to satisfy this flow rate.

As a result, in the spindle device according to the present embodiment, even if the lubricating liquid mixed with foreign matter such as dust is supplied from the fixed side supply passage 14 of the housing 5, the clean lubricating liquid is obtained by removing the foreign matter by the centrifugal action. Only thrust dynamic bearing 4
And since it can be supplied to the bearing clearance of the radial dynamic pressure bearing 3, it is possible to avoid the trouble that the foreign matter is caught in the bearing clearance without providing a filter for filtering the foreign matter. Becomes

When the spindle main shaft of the spindle device of the machine tool is supported by the dynamic pressure bearing, there is a possibility that foreign matter such as cutting powder of the work is mixed in the lubricating liquid discharged from the dynamic pressure bearing. In the spindle device of the present embodiment described above, this lubricating liquid is collected and re-supplied as the lubricating liquid as it is without passing through any filtration filter, and the operation of such a machine tool can be continued. It is possible to reduce the operating cost by significantly reducing Further, since the lubricating liquid can be reused without using the filtration filter, it is not necessary to suspend the operation for cleaning the filtration filter, and the operation efficiency of the spindle device can be improved.

On the other hand, since the centrifugal separation action does not work on the lubricating liquid in the centrifugal separation chamber 12 while the spindle main shaft 2 is stopped, the lubricating liquid containing foreign matter may flow into the supply passage 11. However, in order to eliminate this possibility in the present embodiment, an occlusion body 19 that absorbs and retains the lubricating liquid is provided at the inlet of the supply channel 11 in the centrifuge chamber 12 to prevent the spindle main shaft 2 from rotating during rotation. The occluded body 19 was constituted so that the cleaned lubricating liquid was contained therein. As the occlusion body 19, a cloth made of highly water-absorbent fibers, a porous resin, ceramics, a metal, or the like can be used.

According to the construction in which such an occlusion body 19 is provided in the centrifuge chamber 12, the lubricating liquid cleaned during the rotation of the spindle 2 is absorbed and retained in the occlusion body 19. Even when the spindle main shaft 2 is started after the rotation thereof is once stopped, the spindle main shaft 2 is started while supplying the clean lubricating liquid contained in the occlusion body 19 to the bearing gap of the thrust dynamic pressure bearing 4. It can be performed.

Next, FIG. 5 shows a second embodiment of the present invention, in which the present invention is applied to a bearing portion of an impeller of a cascade pump. This cascade pump is configured to rotate an impeller 31 housed in a housing 30 and to pump a liquid in a working passage 32 formed in the housing 30. A motor 33 that drives the wheel 31 is provided integrally with the housing 30 and the impeller 31. That is, the motor rotor 33 a is directly fixed to the impeller 31, while the housing 30 that accommodates the impeller 31.
A motor stator 33b is fixed to the motor rotor 33b, and the impeller 31 is directly driven to rotate by a drive motor 33 composed of the motor rotor 33a and the motor stator 33b. In FIG. 5, the center of rotation of the impeller 31 is shown by a chain line, and the lower side of the center of rotation is omitted.

A plurality of action grooves 34 are arranged along the circumferential direction on the outer circumference of the impeller 31. This working groove 34
Is formed on one corner where the side surface and the outer peripheral surface of the impeller 31 intersect, and is formed by cutting out the corner of the impeller 31 in a fan shape. On the other hand, the working passage 32
Is formed so as to accommodate the formation region of the action groove 34 of the impeller 31, and the cross section of the action passage 32 widely surrounds the outside of the action groove 34 of the impeller 31.

FIG. 6 is a sectional view showing the relationship between the working passage 32 formed in the housing 1 and the impeller 31. The working passage 32 is provided so as to surround about 80% of the outer circumference of the impeller 31, and a suction passage 35 for guiding the liquid to the working passage 32 is provided at one end thereof, and a pumped liquid is provided at the other end thereof. The discharge passage 36 for discharging is connected. In addition, the suction passage 35 and the discharge passage 36
A partition wall 37 is formed between the partition wall 37 and the outer wall surface of the impeller 31 (for example, 20 μm).
(To the extent) opposite. As a result, the working passage 3
The suction side and the discharge side of 2 are separated from each other to prevent the liquid in the discharge passage 36 side from returning to the suction passage 35 side.

In order to prevent the liquid in the working passage 32 from leaking from the side surface of the impeller 31 toward the center of rotation, on the inner diameter side of the working passage 32, the impeller 31 and the housing 30 have a very small gap. Are facing through. In this embodiment, the thrust dynamic pressure bearing 38 is formed between the side surface of the impeller 31 and the housing 30 by using this gap as a bearing gap. Further, the back surface of the impeller 31 provided with the motor rotor 33a also faces the housing 30 with a slight gap, and constitutes a thrust dynamic pressure bearing 39 having the gap as a bearing gap. As a result, the impeller 31 is restricted from moving in the axial direction by the pair of thrust dynamic pressure bearings 38 and 39.

Similar to the first embodiment, the dynamic pressure grooves formed on both side surfaces of the impeller 31 press the lubricant in the bearing gap radially inward as the impeller 31 rotates. The spiral groove of the pump-in pattern and the so-called pump-out pattern spiral groove that pressurizes the lubricant in the bearing gap outward in the radial direction as the impeller 31 rotates are used. It is supplied to the bearing gap from the supply flow path 40 opened in the impeller at the boundary of the groove. Therefore, a part of the lubricating liquid guided from the supply passage 40 to the bearing gaps of the thrust dynamic pressure bearings 38, 39 is sent to the inner side in the radial direction by the spiral groove of the pump-in pattern, and the bearing of the radial dynamic pressure bearing described later is obtained. It flows into the gap. Further, the other lubricating liquid is sent to the outside in the radial direction by the spiral groove of the pump-out pattern, and is discharged from the outer peripheral edge of the impeller 31 into the working passage 32. Therefore, during rotation of the impeller 31, there is no concern that dust or the like will enter from the working passage 32 into the bearing gap between the thrust dynamic pressure bearings 38, 39.

The inner peripheral surface of the impeller 31 is the housing 3
0 and a radial dynamic pressure bearing 41, which is opposed to 0 through a slight gap, and which serves as a bearing gap. A dynamic pressure groove for pressurizing the lubricating fluid in the bearing gap is formed in the housing 30, and when the impeller 31 starts rotating,
A high-pressure fluid lubrication film is formed in the bearing gap, and the rotation of the impeller 31 is supported in a non-contact state with the housing 30. Here, the dynamic pressure groove is formed so as to press the lubricating liquid in the bearing gap toward the center of the impeller 31 in the axial direction (width direction) as the impeller 31 rotates. The white arrows in FIG. 5 indicate the flowing direction of the lubricating liquid in the bearing gaps of the thrust dynamic pressure bearings 38, 39 and the radial dynamic pressure bearing 41.

In each of the thrust dynamic pressure bearings 38 and 39 and the radial dynamic pressure bearing 41, the liquid which is pumped in the working passage 32 is used as the lubricating liquid. The housing 30 is formed with a fixed-side supply passage 42 for extracting the lubricating liquid from the working passage 32, and the lubricating liquid is supplied to the impeller 31 from the fixed-side supply passage 42.
The fixed side supply passage 42 communicates with the bearing gap of the radial dynamic pressure bearing 41. Further, the impeller 31 is provided with an introduction flow path 43 facing the fixed side supply path 42, and the introduction flow path 43 communicates with a centrifugal separation chamber 44 provided in the impeller 31. The lubricating liquid sent from the fixed-side supply passage 42 flows into the introduction passage 43 through the bearing gap of the radial dynamic pressure bearing 41, but as described above, the lubricating liquid is impeller in the bearing gap of the radial dynamic pressure bearing 41. Since the pressure is applied toward the center in the axial direction of 31, i.e., toward the opened position of the introduction flow passage 43, the lubricating liquid ejected from the fixed side supply passage 42 into the bearing gap of the radial dynamic pressure bearing 41 is the bearing gap. It cannot diffuse inside, and most of it will enter the introduction flow path 43. Further, the lubricating liquid flowing from the bearing gaps of the thrust dynamic pressure bearings 38 and 39 to the bearing gaps of the radial dynamic pressure bearing 41 also flows into the introduction flow passage 43 of the impeller 31 wheel for the same reason.

In this way, the introduction passage 43 of the impeller 31
The lubricating liquid sent to is supplied to the centrifugal separation chamber 44 provided in the impeller 31. FIG. 7 shows this centrifuge chamber 44.
Is shown. The centrifugal separation chambers 44 are provided at several places in the circumferential direction of the impeller 31, and the lubricating liquid introduced from the introduction flow passage 43 is temporarily stored. A discharge flow passage 45 is provided from the centrifugal separation chamber 44 toward the outer side in the radial direction of the impeller 31, and the discharge flow passage 45 is opened to the working passage 32 on the outer peripheral surface of the impeller 31. In the centrifugal separation chamber 44, a tapered throttle portion 46 is formed toward the discharge flow passage 45. Due to the presence of the throttle portion 46, the lubricating liquid introduced from the introduction flow passage 43 into the centrifugal separation chamber 44 is prevented. The centrifuge chamber 44
It is supposed to temporarily stay inside. Further, the supply passage 40 for supplying the lubricating liquid to the bearing gaps of the thrust dynamic pressure bearings 38, 39 is centrifugally arranged at a position closer to the introduction passage 43 than the discharge passage 45, that is, at the inner side in the radial direction of the impeller 31. It communicates with the separation chamber 44.

When the impeller 31 is rotated by the motor 33, the lubricating liquid in the supply passage 40 is sucked into the bearing gaps of the thrust dynamic pressure bearings 38 and 39, and the lubricating liquid in the centrifugal chamber 44 is supplied. It is sucked into the road 40. Since the centrifugal separation chamber 44 exists at a position displaced from the rotation center of the impeller 31, when the impeller 31 rotates, centrifugal force acts on the lubricating liquid in the centrifugal separation chamber 44. If this cascade pump is used to pump slurry such as grinding fluid containing abrasive grains, the specific gravity of the abrasive grains is larger than the specific gravity of the grinding fluid that becomes the lubricating fluid, so the centrifugal force that acts on the abrasive grains is The centrifugal force acting on the liquid is larger than the centrifugal force. In the rotating centrifugal separation chamber 44, the abrasive particles gather outside the impeller 31 in the radial direction, that is, at a position close to the discharge flow passage 45, and the centrifugal force in the radial direction of the impeller 31 increases. At the inner side, that is, at a position close to the supply flow path 43, there is a clean grinding liquid from which abrasive grains have been removed. That is, the centrifugal separation action acts on the abrasive particles in the grinding liquid, and the grinding liquid supplied from the introduction flow path 43 to the centrifugal separation chamber 44 is the grinding liquid mixed with the abrasive particles and the clean grinding without the mixing of the abrasive particles. It is separated into liquid. And
The grinding fluid containing a large amount of abrasive grains is discharged from the centrifugal separation chamber 44 through the discharge passage 45 and returned to the working passage 32. On the other hand, the clean grinding liquid from which the abrasive grains have been removed is sucked into the supply passage 40 and supplied to the bearing gaps of the thrust dynamic pressure bearings 38, 39.

As a result, in the cascade pump of this embodiment, even if the grinding fluid mixed with abrasive grains is supplied from the fixed side supply passage 42 of the housing 30, only the clean grinding fluid from which the abrasive grains have been removed by the centrifugal separation action is supplied. Can be supplied to the bearing gaps of the thrust dynamic pressure bearings 38, 39 and the radial dynamic pressure bearing 41 as a lubricating liquid, so that the abrasive grains can be supplied to the bearing gaps without providing a filter for filtering the abrasive grains. It is possible to avoid troubles such as being caught.

Even in the cascade pump of the second embodiment, if it is taken into consideration when the impeller 31 is restarted after being temporarily stopped, the supply flow path in the centrifugal separation chamber 44 will be described. An occlusion body 4 which absorbs and holds a lubricating liquid at the inlet of 40
It is preferable that 7 is provided so that the occlusion body 47 contains the lubricating liquid cleaned during the rotation of the impeller 31.

[0038]

As described above, according to the dynamic pressure bearing device of the present invention, since the lubricating liquid is supplied to the bearing gap through the centrifugal separation chamber, the lubricating liquid is supplied to the centrifugal separation chamber. Even if foreign matter is mixed in the lubricating fluid to be used, it is possible to remove the foreign matter from the lubricating fluid by the centrifugal action and to supply only clean lubricating fluid to the bearing clearance. It is possible to avoid troubles such as foreign matter getting caught in the gap, removing foreign matter from the lubricating liquid without using a filtration filter, and continuously removing the foreign matter from the clean lubricating liquid to the bearing gap. Can be supplied to.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Jun Nagano             Teichi, 754 Nakatate, Tamabo-cho, Nakakoma-gun, Yamanashi Prefecture             Kou Co., Ltd. Kofu factory (72) Inventor Shotaro Mizobuchi             Teichi, 754 Nakatate, Tamabo-cho, Nakakoma-gun, Yamanashi Prefecture             Kou Co., Ltd. Kofu factory F-term (reference) 3J011 AA07 BA08 CA02 JA02 KA02                       KA03 MA23 MA27

Claims (5)

[Claims] 1. A fixed member, a rotating member, and a bearing gap into which a lubricating liquid is introduced are formed between the fixed member and the rotating member, and a high pressure is applied to the bearing gap as the rotating member rotates. A hydrodynamic bearing that forms a fluid lubrication film and rotatably supports the rotating member with respect to a fixed member; and a centrifuge chamber provided in the rotating member at a position displaced from the center of rotation of the rotating member, An introduction flow path for guiding the lubricating liquid to the centrifuge chamber, a discharge passage extending from the centrifuge chamber to the outer side in the radial direction of the rotary member, and an inner diameter side of the discharge passage connected to the centrifuge chamber And a supply passage for supplying the lubricating liquid from the centrifugal separation chamber to the bearing gap of the dynamic pressure bearing. 2. The rotating member comprises a rotating shaft and a thrust disk fixed to the rotating shaft, and the thrust disk, together with the fixing member, constitutes a thrust dynamic pressure bearing, while the centrifuge chamber is thrust. The hydrodynamic bearing device according to claim 1, wherein the hydrodynamic bearing device is provided on a disc. 3. Between the centrifuge chamber and the discharge passage,
The dynamic pressure bearing device according to claim 1, further comprising a throttle portion for adjusting a flow rate of the lubricating liquid flowing into the discharge passage. 4. The dynamic pressure bearing device according to claim 1, wherein a lubricant storage material is provided in the supply passage. 5. In the bearing gap of the dynamic pressure bearing, the lubricating liquid is pressurized in a direction of sucking the lubricating liquid in the supply passage into the bearing gap as the rotating member rotates. The dynamic pressure bearing device according to claim 1.